Apparatus for vaporizing a developer medium in developing devices for light-sensitive materials

ABSTRACT

This invention relates to an apparatus for vaporizing a developer medium from a solution, in a developing device for light-sensitive material, comprising heating rod means, at least two substantially concentric pipe means surrounding said rod means and having closed ends and elongated aperture means therein, inlet means on the outer pipe means, outlet means on the inner pipe means, and aperture means connecting said outer and inner pipe means, whereby a pool of solution is formed in contact with said heating rod means when said apparatus is operated in a horizontal position.

United States Patent 11 1 Marx Sept. 23, 1975 [5 APPARATUS FOR VAPORIZING A 2,532,184 11/1950 Massimbene 34/162 DEVELO E MEDIUM IN DEVELOPING 2,887,942 5/l959 Frantz 354/300 DEVICES FOR LIGHTSENSITIVE 3,748,995 7/1973 Schroter et al. 354/300 MATERIALS FOREIGN PATENTS OR APPLICATIONS Inventor; Gerhard Mam Taunusstein 1,099,525 H1968 United Kingdom 354/300 Germany Primar Examiner-Charles .l. M hre [73] Asslgnee: Hoechst Aktlengesenschafl Assista z t Exami'nerTheophil W. Streule, .lr.

Germany Attorney, Agent, or F1'rmJames E. Bryan [22] Filed: Feb. 25, 1974 21 Appl. No.: 445,470 ABSTRACT This invention relates to an apparatus for vaporizing a [30] Foreign Application Priority Data developer medium from a solution, in a developing device for light-sensitlve material, compr1s1ng heatmg Feb. 28, 1973 Germany 2309851 rod means, at least two Substantially concentric pipe means surrounding said rod means and having closed 2% 165/155; Q ends and elongated aperture means therein, inlet i .f t d means on the Outer means, Outlet means on the 1 d 0 seal-2d] 165/ inner pipe means, and aperture means connecting said 165/ 354/299 9 34/162 outer and inner pipe means, whereby a pool of solu- 219/271 6 tion is formed in contact with said heating rod means References Cited said apparatus is operated in a horizontal posi- UNITED STATES PATENTS 2,218,097 10 1940 Rhodes /155 6 l D'awmg figure APPARATUS FOR VAPORIZING A DEVELOPER MEDIUM IN DEVELOPING DEVICES FOR LIGHT-SENSITIVE MATERIALS This invention relates to an apparatus for vaporizing a developer medium from a solution in developing devices for light-sensitive materials. In particular, an ammonia/water vapor mixture is vaporized from an aqueous ammonia solution. However, in accordance with the invention, it is also possible to use other developer solutions. The apparatus of the invention is particularly suitable for use in a developing device constituting part ofa photocopying machine. It also may be employed in developing devices for the microfilm field.

In some of the hitherto known developing devices, the ammonia/water vapor mixture is produced in a vaporizer channel extending over the width of the device and provided with a heating means. One end of the vaporizer channel is provided with an inlet and the other end with an outlet for the developer solution (German Patents Nos. 860,1 38 and 888,364). The developer solution fed to the vaporizer channel rapidly reaches the temperature prevailing in the channel so that the developer medium is correspondingly rapidly liberated, the liberated quantity of ammonia depending upon the temperature of the channel and on the initial concentration of the developer solution. By the rapid liberation of the gaseous developer medium, a quantity per unit of time is obtained which is substantially larger than the quantity required for the development of the exposed materials. 8

With these Vaporizers, the gaseous developer medium is thus intermittently liberated, i.e. always when a drop is added. The excess developer medium, if it is ammonia, must be drawn off to prevent it from penetrating through the inlet and outlet apertures for the material of the developing device. Another drawback of the known vaporizer channel is that the sudden temperature rise of the developer solution, upon contact with the heated channel, results in intense boiling and thus splashing of the developer solution. The intermittent liberation of the gaseous developer medium and the splashing result in non-uniform development of the material.

The same drawbacks occur when, in developing devices, Vaporizers are used which are in the form of a pipe provided with slots or holes for the discharge of the developer gas into the developing chamber, and the interior of which includes heating rods (German Auslegeschrift No. 1,096,198).

The object ofthe present invention is to provide a vaporizer which assures uniform discharge of the gaseous developer medium and which prevents a sudden temperature rise of the developer solution, which may lead to splashing.

The present invention provides an apparatus for vaporizing a developer medium from a solution, in developing devices for light-sensitive materials, in which a horizontal or approximately horizontal heating rod is provided with at least two concentric or approximately concentric pipes closed at their ends for the formation of at least two chambers. The pipes have apertures on their upper parts and the outer or outermost pipe is provided with at least one inlet and the inner or inner most pipe with at least one outlet for the solution. Between the chambers formed by the pipes, there is at least one connection for the passage of the solution from the outer to the inner chamber.

In contradistinction to the initially described vaporizers, in the vaporizer of the invention the developer solution is not brought at once to the temperature necessary for vaporization but it is warmed up gradually. In this manner, splashing of the developer solution and intermittent liberation of the gaseous developer medium are prevented. Two chambers are formed by the two pipes arranged concentrically or approximately concentrically around the heating rod. When more than two pipes are used, correspondingly more chambers are formed andthe preheating time is prolonged.

The vaporizer formed by the pipes and the heating rod preferably extends over the entire width of the developi'ng device. In the upper part of the pipes, there are apertures for the outlet of the developer medium into the developing device. Preferably, each pipe has a gap at the top extending over almost its entire length. The gaps of the pipes may be staggered with respect to one another.

The composition of the developer medium, i.e. the ratio of the water vapor and the ammonia gas depends primarily on the temperature in the vaporizer. Therefore, a heating rod, adjustable in its heating power, is preferably used for adjusting the composition of the developer gas. By the suitable selection of the flow rate of the developer solution through the vaporizer as well as by means of the adjustable heating power of the heating rod, it is possible to maintain the composition of the developer gas in the developing device constant. If the composition of the developer gas must be changed, which is the case, for example, when different paper or film types are to be developed, this is possible by changing the flow rate of the developer solution as well as by changing the heating power of the heating rod.

The outer pipe is provided with an inlet for the developer solution. When more than two concentrically arranged pipes are used, the outermost pipe is provided with the inlet. The inlet preferably is located at one end of the outer pipe, whereas the connection for the passage of the developer solution from the outer to the inner pipe preferably is located at the other end. It is achieved thereby that the developer solution which passes through the inlet into the outer chamber passes through its entire length and only then passes into the inner pipe. As the connection for the passage of the developer solution from the outer into the inner chamber, an overflow is preferably used. When passing through the outer chamber, the developer solution is already preheated. When it passes into the inner pipe, i.e. when the developer solution comes into contact with the heating rod, it already has a temperature well above room temperature.

The outlet for the non-vaporized developer solution, relative to the overflow between the outer and the inner pipe, is located at the opposite end of the inner pipe. After passing into the inner chamber, the developer solution passes along the heating rod through the entire length of the chamberv The developer solution which does not vaporize leaves the vaporizer through the outlet at the inner pipe, which outlet preferably is an overflow.

When more than two pipes arranged around the heating rod are used, the inlet, the overflows, and the outlet, insofar as they are in a successive order, are staggered with respect to one another so that the developer solution passes through each pipe in its entire length before it passes into the next inner pipe. By using more than two pipes arranged around the heating rod, the preheating path of the developer solution is further prolonged.

The temperature which the developer solution attains before it passes into the inner or innermost pipe and comes into contact with the heating rod may be varied. It may be varied, for example, by an elongation of the preheating path, or by the selection of the mate rial for the pipes, and by the form of the pipes. One can use pipes with grooved surfaces, for example, and thus obtain an enlargement of the surface of the pipe, which leads to an increased heat transfer.

The invention will be further illustrated by an exemplary embodiment and by way of the accompanying drawing. The drawing is a perspective view, partially in section, of one embodiment of the vaporizer of the invention.

The vaporizer is composed of the heating rod 1 and the two pipes 2 and 3 arranged around it. At the top, the pipes 2 and 3 have the gaps 4 extending almost over their entire lengths and serving for the discharge of the ammonia gas/water vapor mixture into the developing device. The two pipes 2 and 3 arranged around the heating rod 1 form the inner chamber 5 and the outer chamber 6. At one end of the outer pipe 3, there is the inlet 7 for the ammonia water. At the opposite end, the inner pipe 2 is provided with the overflow 9 for the ammonia water 8 from the outer chamber 6 into the inner chamber 5. The inner pipe 2 has two outlets 10 for the non-vaporized ammonia water. The outlets 10, relative to the overflow 9, are located at the opposite end of the inner pipe 2. In order to enlarge the surface of the inner pipe 2 and thus to increase heat transfer, the surface of the inner pipe 2 is provided with the grooves 11. The heating rod 1 preferably bears against the bottom of the inner pipe 2.

The ammonia water 8, fed by means ofa proportioning pump (not shown) through the inlet 7 into the outer chamber 6, initially is at room temperature. When it passes through the outer chamber 6, the ammonia water 8 is warmed up. The temperature which the ammonia water 8 has attained when it passes through the overflow 9 into the inner chamber 5, depends primarily upon the conductivity of the inner pipe 2 and upon its surface area. In the inner chamber 5, the ammonia water 8 contacts the heating rod 1, whereby it is brought to the temperature necessary for vaporization. The ammonia water not vaporized upon passage through the inner chamber 5 leaves the vaporizer through the outlets 10.

It will be obvious to those skilled in the art that many modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.

What is claimed is:

1. An apparatus for vaporizing a developer medium from a solution, in a developing device for lightsensitive material, comprising heating rod means,

at least two substantially concentric pipe means surrounding said rod means and having closed ends and elongated aperture means therein,

inlet means on the outer pipe means,

outlet means on the inner pipe means,

and aperture means connecting said outer and inner pipe means, whereby a pool of solution is formed in contact with said heating rod means when said apparatus is operated in a horizontal position.

2. An apparatus according to claim 1 including groove means on the surface of said inner pipe means.

3. An apparatus according to claim 1 in which said heating rod means contacts said inner pipe means over the length thereof.

4. An apparatus according to claim 1 in which said elongated aperture means extend substantially over the entire length of said pipe means.

5. An apparatus according to claim 1 in which said heating rod means is adapted to be operated at varying heating power.

6. An apparatus according to claim I in which saidsaid apparatus. 

1. An apparatus for vaporizing a developer medium from a solution, in a developing device for light-sensitive material, comprising heating rod means, at least two substantially concentric pipe means surrounding said rod means and having closed ends and elongated aperture means therein, inlet means on the outer pipe means, outlet means on the inner pipe means, and aperture means connecting said outer and inner pipe means, whereby a pool of solution is formed in contact with said heating rod means when said apparatus is operated in a horizontal position.
 2. An apparatus according to claim 1 including groove means on the surface of said inner pipe means.
 3. An apparatus according to claim 1 in which said heating rod means contacts said inner pipe means over the length thereof.
 4. An apparatus according to claim 1 in which said elongated aperture means extend substantially over the entire length of said pipe means.
 5. An apparatus according to claim 1 in which said heating rod means is adapted to be operated at varying heating power.
 6. An apparatus according to claim 1 in which said inlet means Is located adjacent one end of said apparatus, and said aperture means connecting said outer and inner pipe means is located adjacent the other end of said apparatus. 